Apparatus for the removal of dewdrops from a dewed plate member

ABSTRACT

This invention relates to improvements in and relating to an apparatus for the removal of accumulated dewdrops on a plate member, such as automotive front or windshield glass, mirror surface, gauge board or the like, by use of a hot airblast distributed over the dewed surface of the plate member. The apparatus according to this invention is characterized by the provision of a plurality of parallel rows of elongated blasting air-nozzle openings separated a lateral distance from each other, for the delivery of airblasts arranged in layers towards the glass surface.

United States Patent [72] Inventors Norio Mutoh;

Kenji Fuuikake, both of Nagoya, Japan [21 1 Appl. No. 36,537

[22] Filed May 12,1970

[45] Patented Sept. 28, 1971 [73] Assignee Kabushiki Kaisha Toyoto ChuoKenkyusho Nagoya-shi, Aichi-ken, Japan [32] Priority May 12, 1969 [33]Japan [54] APPARATUS FOR THE REMOVAL OF DEWDROPS FROM A DEWED PLATEMEMBER 2 Claims, 10 Drawing Figs.

[52] U.S.Cl...

so FieldotSearch .11: 34/148;

[56] References Cited UNITED STATES PATENTS 2,894,443 7/1959 Rasmussen98/2.08 3,177,794 4/1965 Laing 98l2.09

Primary Examiner-Carroll B. Dority, Jr Attorney-Sughrue, Rothwell, Mion,Zinn & Macpeak ABSTRACT: This invention relates to improvements in andrelating to an apparatus for 'the removal of accumulated dewdrops on aplate member, such as automotive front or windshield glass, mirrorsurface, gauge board or the like, by use of a hot airblast distributedover thedewed surface of the plate'memberr The apparatus according tothis invention is characterized by the provision of a plurality ofparallel rows of elongated blasting air-nozzle openings separated alateral distance from each other, for the delivery of airblasts arrangedin layers towards the glass surface.

PATENTEU SEP28 19H SHEET 1 BF 2 PATENTED SEPZBISYI 3,608,469

' sum 2 [IF 2 FlG.4

RATIO OF DEW-REMOVED SURFACE LENGTH,Xl/XO l L 1 l NOZZLE OPENING RATIO,LO/(LHLZ) APPARATUS FOR THE REMOVAL OF DEWDROPS FROM A DEWED PLATEMEMBER This invention relates to improvements in and relating to anapparatus for the removal of accumulated dewdrops on a plate member,such as automotive front or windshield glass, mirror surface, gaugeboard or the like, by use of a hot airblast distributed over the dewedsurface of the plate member.

The formation of dewdrops on a glass or the like plate occasionallyappearing during its use in the atmospheric air and providing anobstacle to its see-through nature in the case of an automotivewindshield glass, as an example, or causing dimness of the reflectingsurface of a mirror glass, for instance, takes place, as is commonlyknown, in such a case that the temperature of the glass surface dropsbelow the dewpoint, on the absolute humidity of the atmospherecontacting the glass surface attains to the saturated one at the glasstemperature. For the removal of the dewdrops thus formed, it has beenalready known to heat up the glass. As an alternative counter measure,it has also been proposed to form a dry-air layer having a lowerrelative humidity than the absolute one of the atmosphere, foraccelerating the evaporation of the formed dewdrops; keeping the glasssurface at a higher temperature than the dewpoint of the atmosphere;and/or preventing access of the wet atmosphere to the glass surface.

A commonly employed measure for attaining the above purpose in theautomotive vehicle is to use an airblast which has been preheated by acertain heating means or a heat exchanger, and/or passed through adehumidifier and is delivered through a duct from a plurality of nozzlesarranged in parallel with each other, in the lateral direction of thewindshield, as an example, and at an inclined angle relative thereto,for directing the delivered hop airblast against the glass surface, soas to heat up the glass surface above the dewpoint and to form aninsulating airflow layer over the surface.

In order to increase the dew-removal efficiency, the following threemeasures are conceivable. The first one is to improve the nature of thehot blast air by elevating the temperature thereof or by lowering thehumidity thereof. The second one is to increase the blasting speed inorder to elevate the temperature rise of the glass surface. The thirdmeasure is to increase the mean thickness of the blasted and distributedhot air layer,

as measured perpendicularly to the glass surface. When the.

first measure should be employed, the heating means and the dehumidifiermust be intensified in their capacity, which will cause, however, asubstantial increase of the investment in this respect. For therealization of the second measure, the blasting air quantity per unit oftime must be increased and the capacity of the blower and the drivingpower source should naturally be intensified. In addition, the capacityof the heat exhanger or that of the air-heating means must be increasedto an unacceptable degree. If the third measure is employed, the nozzleopening must be correspondingly enlarged and foreign bodies may bedropped into the opening, which would result in a dangerous accident. Inaddition, a substantial enlargement of the nozzle opening will reducethe blasting air speed. In compensation thereof, the capacity of theblasting blower must be increased again to an unacceptable degree.

The primary object of the invention is to provide an apparatus for theremoval of dewdrops from a dewed surface with a smallest possiblequantity of blast air directed over a broadest possible area of thesurface, while obviating the aforementioned conventional drawbacks.

In order to realize the above object, the mechanism according to thisinvention comprises a plurality of parallel rows of air-blasting nozzlesdisposed parallelly to each other in the longitudinal direction of saidnozzle opening on an imaginary plane connecting the outlets of thenozzles, so as to direct the blasting airflows delivered therefromagainst the dewed surface substantially in the form of multilayers.

In this way, dewdrops may be removed from the dewed surface in a highlyefficient way. It should be mentioned that the apparatus according tothis invention is especially suitable for the removal of dimmingdewdrops from the automotive windshield glass.

These and further objects, features and advantages of the invention willbecome more apparent from the following detailed description of severalpreferred embodiments of the invention which are shown in the highlysimplified schematic way and in comparison with a comparativeconventional apparatus. In the drawings:

FIG. 1 is an elevational and sectional view of essential parts of acomparative conventional apparatus shown for the purpose of comparison.

FIG. 2 is a similar view to FIG. 1, showing a first embodiment of theinvention.

FIG. 3 is a similar view to FIG. 2, showing a second embodiment of theinvention.

FIG. 4 is a top plan view of FIG. 2, wherein, however, a glass plate tobe protected is shown as partially sectioned and partially simplified.

FIG. 5 is similar view to FIG. 4, showing a top plan view of FIG. 3.

FIG. 6 is an explanatory sectional view for the explanation of the modeof the mode of the blast airflow attainable when following theconventional teachings.

FIG. 7 is a similar view to FIG. 6, illustrating, however, the teachingsof the present invention.

FIG. 8 is an explanatory chart showing the dew-removal effect of theinvention, as ascertained by our practical experiments.

FIG. 9 is a schematic and partial section of a third embodiment of theinvention.

FIG. 10 is a similar view to FIG. 9, yet showing a fourth embodiment ofthe invention.

Referring now to the accompanying drawings, the invention will bedescribed in detail and in a comparative way with a conventionalcomparative apparatus.

In FIG. 1, a representative conventional apparatus shown, wherein thenumeral 10 represents an automotive windshield glass shown in sectionand only partially simplification. Although only one nozzle is shown at11 in the drawing only for simplicity, there is provided a row ofsimilar nozzles arranged in an imaginary plane, substantiallyperpendicular to the drawing paper. Each of these nozzles 11 is flangedat its top end and fixedly mounted on a conventional dash panel 15 of anautomotive vehicle, not shown. The nozzle 11 n'gidly and tightly fittedat its reduced lower end in the top end of a duct 13. These ducts 13,although shown only one for simplicity, are fed each with a properlyheated and dehumidified air stream by passing it through a heat exhangeror a heater, not shown, preferably from a common distributor, not shown.This stream is shown in a schematic way by an arrow A in FIG. 1.

The axis X of the nozzle 11 or a common plane including all of theseaxes forms and acute included angle a, as shown, with the inclinedlymounted shield 10 so that all the airblasts, shown by several smallarrow B for the representative nozzle 11 and delivered from the outlettop-end openings 12, are brought at first into collision against theback surface of the glass and then distributed in the form of a flowingair layer over the substantial area of the glass back surface whichdirects towards right in FIG. 1 or towards the drivers seat, althoughnot shown. By this hot air blasting, the glass back surface is heated upabove the dewpoint of the atmosphere prevailing within the vehiclecabin, not shown, and a flowing dry air layer is formed over the glasssurface for preventing access of the cabin atmosphere to the glass 10.

In FIG. 2, first embodiment is shown. In this embodiment, the numerals13, 15' and 16 and the symbol A denote similar members and theblastairflow shown in the foregoing at l3, l5 and 10, and at A respectively.

The nozzle representatively shown at 30 is so modified from theconventional one shown in FIG. 1 that its upper opening 40 is dividedinto two parallel outlet passages 40a and 40b by the provision of aseparator wall 14 extending between the both ends of the nozzle-definingwall, thus substantially in the direction perpendicular to the plane ofthe drawing paper. This divided structure is clearly seen from FIG. 4.In this way, two rows of nozzle outlet openings 40a and 40b are formedwhen seen the whole arrangement of the nozzles 30. In FIG. 4, however,only two of a number of nozzles 30 arranged, as may well be supposed,along an imaginary curve which is parallel to the elongated and curvedwindshield glass 16. As is shown, the nozzle division into two separatedoutlet openings 40a and 40b is made in the lateral directionperpendicular to the windshield 16.

Although the overall nozzle width LO measured at the top outlet endopening is selected to be longer than the effective width L of theforegoing nozzle 11 as measured at the top outlet opening 12 thereof,but the sum of the outlet widths L1 and L2 of the divided two nozzleoutlets 40a and 40b is selected to be equal to said L. Therefore, theeffective discharge area of these outlet openings 40a and 40b in thisfirst embodiment is equal to that of the conventional nozzle arrangementshown in FIG. 1, because of the elongated rectangular configuration ofeach of the airblast openings. The corresponding flows of the airblastsare shown by two groups of small arrows C1 and C2.

In the second embodiment shown in FIGS. 3 and 5, two separated nozzleelements 31 and 32 are provided which are arranged in parallel to eachother as seen from FIG. 5. The common axis to these nozzle elementsextends again in parallel to the windshield glass 16' the respectiveoutlet openings of these nozzle elements 31 and 32 attached againfixedly to the dash panel 15" are shown at 41 and 42, respectively. Atthe lower ends of these nozzle elements 31 and 32 are slid tightly intothe upper ends of two branches 17a and 17b of a dry-airsupply duct 17.The blasting air flows flowing through the respective nozzle passagesare shown at D1 and D2, respectively. The arrow A represents the samemeaning as before.

The sum of the respective widths L1 and L2 of the outlet openings 41 and42 is selected again to be equal to the said width L. Although onlythree sets of the nozzle assemblies are shown in FIG. 5, the numberthereof may be increased, as the occasion may desire.

Now return to FIG. 4, the two airblast openings 40a of the two nozzleassemblies are arranged in a curved row which is parallel to thewindshield glass 16.

The remaining two outlet openings 40b are equally arranged in a curvedrow. As seen, these curved rows are parallel to each other. It will beeasily seen that these two-row arrangement of the nozzle-dischargeopenings extends along substantially the whole length of the glass 16which is shown partially section and partially in a highly simplifiedway by chain-dotted lines. Therefore, the number of the nozzleassemblies may be increased, as the occasion may desire.

In FIG. 5, the discharge-outlet openings 41 of the three successivenozzle elements 31 are arranged in a curved row, and similarly theremaining three openings 42 are positioned again in a curved row. Asseen, these rows are parallel to each other and to the curved elongationof the windshield 16 which is shown again partially in section andpartially in a schematic way.

In the embodiments shown in FIGS. 25, air is heated upon a suitabletemperature which is higher than the dewpoint of the atmospherecontacting the windshield by passing preparatorily through a heatexhanger or an electric heater, not shown, and further through adehumidifier, again not shown, thence introduced, as schematically shownby respective arrows A through the ducts 13; 17 into the blast-nozzlepassages 40a, 40b; 41, 42, respectively.

From the respective blast openings, airstreams are blasted against thewindshield glass 16; 16'. In this case, it should be noted that betweenthe pair of blast openings 40a and 40b or 41 and 42, there is a certainidle zone shown at 14a (FIG. 2) or 15a (FIG. 3), respectively, so thatthe combined airblast stream as observed at a direct downstream positionfrom said opening will substantially attain the overall lateral width L0or L0 fully covering the two rows of said blast openings. As

practically observed, although the blast airstreams are not of therectified nature, these are influenced by the very presence of a lowdynamic pressure zone 18 (FIG. 7) positioned above the idle area 14a or15a, and the initially separated blast streams are subjected to asectional contraction effect. Therefore, the combined blast stream has ashorter width than the combined lateral length LO" shown in FIG. 7 whichlength corresponds to that shown at LO (FIG. 2) or L0 (FIG. 3). Thanksto this phenomenon, the combined and contracted blast airstream has asubstantially strong penetration performance in comparison with animaginary airblast which is assumed to be delivered from a singleimaginary nozzle having a lateral width of blast opening correspondingto a sum of L1 plus L2" which is equal to L (FIG. 1) set forthhereinbefore.

FIG. 6 illustrates the dynamic effect of a conventional single-nozzleairblast. The blast stream delivered from the discharge opening 12 ofthe nozzle 11 represents a considerable amount of branched-off swirlsdirectly upon delivery from the discharge opening and in the outsideperipheral zone of the main body of the blast stream, as shown at 20 inFIG. 6 as an example. This phenomenon means kind of disadvantageousdivergence effect which affects adversely upon the desirous penetrationpower of the blast stream in advance of its arrival at the dewed surfaceof the windshield glass 10.

In the improved apparatus according to this invention, shown in FIG. 7,however, attracting swirls 19 are generated in the dynamically lowpressure zone 18, thereby the both blast streams delivered from theseparated delivery openings 40a (or 41) and 40b (or 42) are broughttogether and subjected to a cross-sectional contraction to a substantialdegree, as was referred to above. Therefore, the overall width of thecombined blast stream has a smaller lateral dimension than LO" (FIG. 7),thus providing once a powerful penetrating power and, after then only,the blast being subjected to a gradual divergence. In this way, thedewdrops removal effect will be considerably intensified according tothe novel teachings of the present invention.

The chart shown in FIG. 8 clearly demonstrates the aforementionedinventive effect as ascertained by our practical and comparativeexperiments from which the comparative dewremoval effect expressed interms of the ratio of dew-removed surface lengths was plotted againstthe nozzle-opening ratio expressed by LO/CL1+L2).

For carrying out the experiments, a conventional apparatus as shown inFIG. 6 was used for comparison. In this case, the outer surface of thewindshield glass 10 was kept at a low temperature, generally expressedby t which is lower than the dewpoint of the cabin atmosphere so as toform dewdrops on the back surface of the glass. Then, a continuousairblast temperature generally expressed by T which is higher than saidlow temperature I was delivered from the nozzle opening 12 against thedewed back surface of the same glass 10. Then, the cleared-away area ofdew was measured in its lateral length of the glass which is expressedby XO herein.

Next, the experimental data such as the low glass surface temperature t,the air-blasting temperature T; and the blastair-delivery rate wereunchanged and the sole nozzle opening was divided into two, the nearestone to the glass being fixedly positioned, and then the remaining orfar-positioned nozzle opening was arranged movable, so as to makeseveral experiments with different mutual distances between the bothnozzles divided. The widths of the divided nozzles were set to L1 andL2", as before, and the relation: L1"+L2"=L was preserved, as in thecase of the apparatus shown in FIG. 7. In this way, the dew-removaleffect expressed in terms of X1 /X0 was plotted against the nozzleopening ratio: LO/L1+L2), as shown.

The curve 50 shown in the chart, FIG. 8, was obtained with L1" and L2"being 3 mm., respectively; with the airblast rate being 0.036 m./sec.per unit cross-sectional area of the blast opening. The results werecompared with the same blasting ratio with a single nozzle having alateral width L of 6mm.

The next upper curve 51 represents the results of several experimentswith two separated, yet parallel-arranged nozzle openings having LI" andL2" of equal 6 mm., respectively. The airblast rate was set to 0.036m./sec. per unit area of nozzle opening. The results were compared withthose of similar experiments carried out on a unified nozzle having alateral opening length of 12 mm.

The uppermost curve 52 represents the results of several experimentswith two separated, yet parallel-arranged nozzle opening having L1" andL2" of equally 6 mm., respectively. The airblast ratio was set to 0.024milsec. per unit opening area of nozzle. Comparative unified nozzle hada lateral width of 12 mm.

From the chart shown in FIG. 8, it will be clearly observed that withL1+L2+L; and with a certain constant airblast rate, the apparatusaccording to this invention will provide the ratio: L0/(Ll+L2) beinglarger than unity, or more specifically, a division of a nozzle openinginto two elemental ones separated through a separating distance fromeach other will provide the ratio: Xl/XO being larger than unity whichmeans that the lateral length of the dew-removal area is increasedsubstantially in comparison with the similar length obtainable with asingle unified nozzle.

The lateral length of dew removal representing the dewclearing-awayperformance of the apparatus according to the invention will become, asseen from the chart of FIG. 8, substantially to that of the unified solenozzle opening, when the ratio: L0/(L1+L2) exceeds 1.3.It will befurther seen that the dew-clearing-away performance of the apparatus is20-80 percent larger than that of the prior art sole-nozzle-row-typemachine, within such range, indeed, as extending between 1.3 and 3.0 ofthe ratio: L0/(L1+L2). In this chart, the critical point wherein theratio: Xl/X0 becomes unity will be at 3.4; 3.9 or 4.3, respectively, ofthe ratio: C0/(L1+L2) for the curve 50; 51 or 52.

In the embodiments mentioned herein in the foregoing, the nozzle-outletopenings are arranged in two parallel rows. As seen in FIG. 9, however,the number of rows of nozzle-opening groups may be increased to three.The thus dividedly distributed airblast openings are shown at 43, 44 and45. It may naturally be conceivable to further increase the number ofthe rows to a still more numerous one. The respective angle ofinclination of the mean blast airflows delivered from the openings 43-45or a kind of angle of attack is shown at 91, 62 and 63, respectively. Apreferred arrangement of these inclination angles 61-03 is such as shownthat with the longer distance from the windshield 16" to the respectiveopenings 43-45, they become smaller than each of the preceding one.These angles may be varied in consideration of the covering area of thewindshield glass and the inclination of the latter relative to thehorizontal.

The invention is not limitative to its application for dewremovalservice for the automotive windshield glass.

The dew-removal service by use of the inventive apparatus may be carriedout on a mirror 25 fitted on the wall of a bathroom, washroom or thelike in which a humidity-rich atmosphere prevails. In this case,dewdrops can be effectively removed by blasting dried and heatedairstreams from two rows of nozzle openings representatively shown onlytwo nozzles at 46 and 47 against the surface of mirror 25 through acommon distributor box 26 fluidically connected through a heater and adehumidifier, not shown, with a proper outside supply source, accordingto the novel teachings of the invention set forth hereinbefore.

As a further example, a show-window glass, gauge board or the like platemember may equally be removed of formed dewdrops as the condensate fromaqueous humidity contained in a gaseous atmosphere such as nitrogen,argon or the like, kept in contact with the plate.

Therefore, the term air used in the foregoing description can be read asgaseous atmosphere when applicable without pre'udice. D

It will thus be seen that by use of the inventive dew-cleanng mechanismcomprising a plurality of parallel rows of gas-blasting nozzles disposedparallelly to each other in the longitudinal direction of the nozzleopening on an imaginary plane connecting the outlets of the nozzles, soas to direct the blasting airflows delivered therefrom against the dewedsurface substantially in the form of multilayers, the dewdrops condensedfrom the ambient atmosphere rich of aqueous humidity on the surface caneffectively be cleared off.

According to our experiment, the dew-removal effect thus obtained ishigher 20-100 percent that the case of single-row arrangement ofblasting nozzles. This efficiency elevation was observed in terms of thedew-removed surface areas in comparison with the use of a conventionalcomparative apparatus shown and described hereinbefore by reference toFIG. 1. Naturally, the apparatus of the invention is utilized forwarming up the glass or the like plate member always above the dewpointof the ambient atmosphere, so as to avoid from the beginning theformation of dewdrops. The thus-formed practically multilayer air or gasshield acts naturally as an insulating means for the prevention ofaccess of the dew-forming gaseous atmosphere from contact with with theplate member. Therefore, the apparatus for dew removal from a platemember constructed according to this invention is highly effective forcooperation with the automotive windshield glass and in theabove-mentioned service.

The embodiments of the invention in which an exclusive property orprivilege is claimed are as follows:

1. An apparatus for the removal and prevention of dewdrops on a glass orthe like plate member by blasting hotair jetstreams against the dewedand dewing surface of the plate member from a nozzle positioned alongone side thereof said apparatus comprising: a plate member, a pluralityof parallel rows of elongated air nozzles laterally spaced from eachother, each of said rows of said nozzles extending in a directionoutwardly from said one side of said plate member and oriented todeliver air in layers towards the surface of said plate member.

2. An apparatus for the removal of formed dewdrops and for theprevention of dew formation on a plate member, preferably made of glassor the like materials, comprising: a plate member, a plurality ofparallel rows of elongated nozzle openings each of, laterally spacedfrom each other said rows being parallel to said plate member andlaterally spaced outwardly therefrom, and a separating means providedbetween each two rows of said nozzle rows.

UNITED STATES PATENT OKFICE CERTIFICATE OF CORRECTION Patent No. 3,608,469 Dated January 18, 1972 Inventor(s) Norio Mutoh et a1 It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Delete: Inventors-Norio Mutoh;

Kenji Fuuikake and substitute therefor-- Inventors-Norio Mutoh;

Kenji Fujikake Delete: As signee: Kabushiki Kaisha Toyoto Chuo Kenkyushoand substitute therefor--Kabushiki Keisha. Toyota Chuo Kenkyusho-;

Signed'and sealed this 1 th day of April 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents -ORM PO-1050(10-69) USCOMM-DC 60378-F'B9 Q U 5 GOVERNMENTPRINTING OFFICE 1 i969 O3fi6-334

1. An apparatus for the removal and prevention of dewdrops on a glass orthe like plate member by blasting hot-air jetstreams against the dewedand dewing surface of the plate member from a nozzle positioned alongone side thereof, said apparatus comprising: a plate member, a pluralityof parallel rows of elongated air nozzles laterally spaced from eachother, each of said rows of said nozzles extending in a directionoutwardly from said one side of said plate member and oriented todeliver air in layers towards the surface of said plate member.
 2. Anapparatus for the removal of formed dewdrops and for the prevention ofdew formation on a plate member, preferably made of glass or the likematerials, comprising: a plate member, a plurality of parallel rows ofelongated nozzle openings laterally spaced from each other, each of saidrows being parallel to said plate member and laterally spaced outwardlytherefrom, and a separating means provided between each two rows of saidnozzle rows.